Conventional electrical outlets to which the prong fittings of extension cords are connected, are mounted in metal outlet boxes, and are provided with a pair of terminal plates which receive screws. In order to connect the terminal plates to the supply line for the outlet box, a short length of insulation is removed from each wire of the supply line, the exposed wire is bent into hook form and inserted between the head of the screw and the terminal plate, whereupon the screw is tightened. In tightening the screw, the turning force exerted by the screw, particularly if the hook end is wrapped in the wrong direction, or if the wire is a multiple stranded wire, can cause the wire hook to spread. Sometimes such spreading is sufficient to cause a ground or short or to make a poor connection. Also sometimes the screw head may project too far and be exposed for engagement with the walls of the outlet box or other object.